The mini fridge currently on the market, i.e., the thermoelectric cooling device which adopts Peltier effect and direct refrigeration by semiconductor, has the characteristics of low power consumption, no bulky compressor, no pollution of noise and Freon, long life, cute appearance, petite size, and portability. It is suitable for both indoor and outdoor use. It is particularly suitable for use by travelers and field workers. It has the function of heating and cooling. In summer, its cooling function can be utilized to keep beverage cold. In winter, its heating function can be utilized to warm up milk, beverage, bread and other food. This kind of product is getting popular among fashionable youth. However, this kind of mini fridge must be used together with power source, and manipulating electric wire and plug can be troublesome even though there is convenient socket such as USB, etc. For travelers and field workers, the fridge cannot be used without external power supply. Since the fridge can only work with power supply, the promotion and application of this kind of mini fridge is restricted.